A liquid crystal display (LCD) device is an example of display devices and has advantages of lightness, thinness, low cost, low power consumption, an excellent junction with an integrated circuit, and the like, and thus is widely used in laptops, monitors, and TV screens. The liquid crystal display device includes a lower substrate including a black matrix, a color filter, and an indium tin oxide (ITO) pixel electrode, and an upper substrate including an active circuit portion including a liquid crystal layer, a thin film transistor, an electricity storage capacitor layer, and an ITO pixel electrode. In the liquid crystal display device, color filters are formed in a pixel region by sequentially laminating a plurality of color filters (in general, formed of three primary colors such as red (R), green (G), and blue (B)) in a predetermined order to form each pixel, and a black matrix layer is disposed in a predetermined pattern on a transparent substrate to form a boundary between the pixels.
A color filter may be fabricated using a pigment dispersion method. According to the pigment dispersion method, a thin film is formed by repeatedly coating a photosensitive resin composition including an alkali soluble resin, a photopolymerization monomer, a photopolymerization initiator, an epoxy resin, a solvent, and other additives as well as a colorant on a transparent substrate provided with a black matrix, exposing a desired pattern to a light, removing an unexposed part with a solvent, and thermally curing the resulting product. This method is actively used to fabricate LCDs for mobile phones, laptops, monitors, TVs, and the like.
However, recently there is increased demand that a photosensitive resin composition for a color filter fabricated using a pigment dispersion method provide high luminance, a high contrast ratio, and the like as well as high color reproducibility and excellent pattern profiles.
A color filter fabricated using a conventional pigment-type photosensitive resin composition can have limited luminance and contrast ratio due to the size of pigment particles. Accordingly, when a photosensitive resin composition includes a highly durable dye with no particles or small primary particles in a predetermined amount or more instead of a pigment, excellent high luminance and high contrast ratio may be accomplished while maintaining the thickness of a conventional pixel compared with the pigment-type photosensitive resin composition. This has been illustrated in Korean Patent Laid-Open Publication No.'s 1999-0007097, 2002-0015650, 2005-0020653, 2008-0138780, and the like. However, a dye used in these arts may accomplish luminance characteristics but also can have poor durability due to a small particle size and molecular weight.
Therefore, there is a need for a new photosensitive resin composition for a color filter having excellent durability as well as high luminance and high contrast ratio.